(Foundation series, Robot series, The Bicentennial Man, The End of Eternity, The Gods Themselves, I, Robot)
Asimov wrote science fiction novels and short stories in sparse, unadorned prose. He was a rationalist and a humanist, and rational thought and rational expression of ideas are paramount in his stories. While his stories have a heavy focus on science, ideas, and philosophy, he also frequently explores themes like social oppression. Asimov also wrote mysteries and nonfiction, and introduced the science fiction mystery.
If you like Asimov’s scifi novels, try:
Arthur C. Clarke (while dissimilar in writing style, Clarke might appeal to fans of classic sci-fi—if you’ve never read any of his work, try his collected stories. Readers who enjoy Asimov’s science writing might want to check out Clarke’s essays)
Robert Heinlein (he completes the Big Three of sci-fi, Asimov and Clarke being the others. Try Starship Troopers, For Us, The Living: A Comedy of Customs or Stranger in a Strange Land to get an idea of his usual themes and style)
Frederik Pohl (if you enjoy Asimov’s writing style you might like Pohl’s work—try Gateway to begin)
Robert Silverberg (if you would like to try something a little different, though still in the category of classic science fiction, try the Majipoor series, beginning with Lord Valentine’s Castle)